Ni-P-(sol)Al2O3 nanocomposite coatings were prepared on Q235 carbon steel substrates by pulse-assisted sol-gel method with duty cycles ranging from 20 to 90 %. The production, microstructural characterization, corrosion resistance, friction, and wear properties of Ni-P-(sol)Al2O3 nanocomposite coating were evaluated. The results show that when the duty cycle is 50 %, the surface quality and corrosion resistance of the composite coating are the best, the hardness is 559.6 HV, the corrosion rate is 2.433 mm y −1 , and the friction coefficient is 0.260. In this study, nano sol was used instead of traditional powder doping. The pulse-assisted sol-enhanced composite coating had good wear and corrosion resistance. This technique can effectively avoid the agglomeration of nanoparticles during the deposition of composite coatings while impacting and leveling the coating surface during the pulse interval to improve coating quality. Meanwhile, the highly dispersed sol saves time and energy consumption of mixed solution without dispersant or stabilizer.

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An innovative brush plating process for preparing coatings on the inner wall of metal pipes is proposed, which aims to solve the limitations of current electroplating technology and improve the performance of the inner walls of metal pipes. While optimizing the process, the effect of working voltage on the microhardness, thickness, surface morphology, corrosion resistance, and elastoplasticity of the Ni coating on the inner wall of the tube was studied under the new process. The results indicate this technique can produce high-quality coatings on the inner wall of pipes in a simple and efficient manner. As the working voltage increases, the surface quality and comprehensive performance of the coating show an increasing trend followed by a decreasing trend. At 12 V, the coating exhibits the highest surface density and uniformity, the lowest surface roughness, the best corrosion resistance, and the maximum microhardness of 575.8 HV, with a corrosion current density of 1.040 × 10−5 A·cm−2, a corrosion rate of 0.122 mm·a−1, the maximum elastic recovery ratio he/hmax of 0.36, and the best deformation resistance. This study demonstrated the effectiveness of this method in improving the durability and functionality of metal pipes and its potential for various industrial applications.

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